Backport pkgutil, pydoc, and doctest from the 2.5 trunk to setuptools
0.7 trunk. (Sideport?) Setuptools 0.7 will install these in place of
the 2.3/2.4 versions (at least of pydoc and doctest) to let them work
properly with eggs. pkg_resources now depends on the 2.5 pkgutil, which
is included here as _pkgutil, to work around the fact that some system
packagers will install setuptools without overriding the stdlib modules.
But users who install their own setuptools will get them, and the system
packaged people probably don't need them.